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KGSSHV Carbon Build Thread


mwl168
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5 minutes ago, JoaMat said:

Those values are all as they should. Also 0 V on leg 2 and -1 V on leg 6 seems reasonable.

If you turn up the trimmer to max resistance - what happens to the offset?

how is 0V at leg2 to resonable when the output is -1.5V?

How is -1V at leg6 resonable when leg 2 and leg3 is 0?

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Well, so now I did a bit different.  I toned balance to be 300mv or less, and then offset to be 500mv or less.  Then I popped in the Servo.  Now one board start out from 0.55 V drop to 150-200mV.  The other board (problem one) started from -1.6V and now dropped to -200 or -300mV

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27 minutes ago, JoaMat said:

One thing at the time. My idea s to find out if the servo makes any difference at all.

Leg 3 is grounded?

by suggesting removing the 120ohm? ....and yes. leg3 is supposed to be grounded, thus why 0v at leg2 should give 0v at leg6

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Well, so what I figured so far was that my DN2540 was partially defected as I removed it and measure 25 ohm something from GD.  Replaced it, and the amp was being tuned when it was very warm.  These numbers fly all over the place.  I let it cool down and readjust....now both the offset is from -50mv to +50 mV from cold to slowly warming up with Servo engaged.

the numbers above should be great ?

 

however as the temperature change, it will drift away :(

Edited by Whitigir
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9 minutes ago, spritzer said:

Yeah, worrying about 1.5V is pretty dumb... 

lol, my apologize :) I am a complete noob regarding Stax and it game :)

 

thank you all all so much for the helps and assists ! So much love in here ! Cheer

Edited by Whitigir
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I have used the opto servo in one T2 and one grounded grid for quite a while and that servo works very well. The offset is mostly in mV range. I can’t tell if it effects the sound negatively.

Offset within 30 or 20 volts is not much to worry about with an electrostatic amplifier with only trimmer/resistor. 1.5V is very good.

If your amplifier has an opto servo then 30 or 20 volts offset is abnormal, even 1.5 V tells you that the amplifier is’t working properly.

7 hours ago, Whitigir said:

....now both the offset is from -50mv to +50 mV from cold to slowly warming up with Servo engaged.

the numbers above should be great ?

No, the numbers are not great. For an opto servo they are normal. Well done!

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18 minutes ago, JoaMat said:

I have used the opto servo in one T2 and one grounded grid for quite a while and that servo works very well. The offset is mostly in mV range. I can’t tell if it effects the sound negatively.

Offset within 30 or 20 volts is not much to worry about with an electrostatic amplifier with only trimmer/resistor. 1.5V is very good.

If your amplifier has an opto servo then 30 or 20 volts offset is abnormal, even 1.5 V tells you that the amplifier is’t working properly.

No, the numbers are not great. For an opto servo they are normal. Well done!

It does drift away as it warm up though.  It can start out as +/- 0.5 or 0.9V and hang around +/- 50mV after 10 minutes.  But then after 20 minutes or so, it would hang around +/- 125 to 320 mV.  I will check again today

Edited by Whitigir
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On 3/24/2017 at 0:05 AM, JoaMat said:

If your amplifier has an opto servo then 30 or 20 volts offset is abnormal, even 1.5 V tells you that the amplifier is’t working properly.

Oh, dear. I use the opto servo on my Carbon, and when warmed-up, the offset hovers between 1.5-1.6V. Both channels. :( Wondering if I should worry about it... I've been using it for months now.

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I couldn't achieve a balance of 0, at least not after closing the top cover, since that causes a slight rise in temperature (even with numerous vent slots). The balance hovers around 3.2V, again depending on the case temperature. After trying for 0 for a while, I figured it's well within spec and stopped.

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Sure your amplifier is well within specifications.:)  I should be more careful with the words. Trying to fix something that isn’t a problem could very well cause real problems.

I’ve five boards with opto servo and they all have offsets close to 0. But that could very well be a lucky coincidence. Next five might change the statistic.

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